The present technology relates to a playback device and method for playing back information recorded on an optical recording medium, and more particularly, relates to technology that reduces the effects of crosstalk from a neighboring track.
Optical recording media in which information is recorded or played back by light irradiation, such as the Compact Disc (CD), Digital Versatile Disc (DVD), and Blu-ray Disc (BD; registered trademark), for example, are widely prevalent.
Even with these optical recording media, there is demand for increased recording capacity as recording media, and for this reason techniques such as making the track pitch narrower have been adopted.
However, making the track pitch narrower leads to the problem of crosstalk from information recorded on a neighboring track.
Among technologies that attempt to reduce crosstalk for an optical recording medium, or in other words improve the signal to noise ratio (S/N) for the readout signal of a target track, there exists technology that sets the groove depth to λ/6, as described in Japanese Unexamined Patent Application Publication No. 2002-269776 and in “Land and Groove Recording for High Track Density on Phase-Change Optical Disks,” Naoyasu Miyagawa, Yasuhiro Gotoh, Eiji Ohno, Kenichi Nishiuchi and Nobuo Akahira, Jpn. J. Appl. Phys. Vol. 32 (1993), pp. 5324-5328, Part 1, No. 11B, November 1993. Note that λ means the recording/playback wavelength.
Particularly, Miyagawa et al. disclose technology that records both on grooves set to a depth of λ/6, and on lands arranged between the grooves. According to such land and groove recording technology with the groove depth set to λ/6, it is possible to reduce crosstalk from a neighboring track (that is, a neighboring land in the case of reading out from a groove, and a neighboring groove in the case of reading out from a land).
Alternatively, for crosstalk reduction, there is also proposed technology that stores the readout signal of a neighboring track, which is used to perform signal processing to cancel crosstalk for the readout signal of the readout track.